But the leaders say the objectives of the referendum are long-term and involve stalled talks with Moldova on the region's future that are being mediated by the Organisation for Security and Cooperation in Europe.

Trans-Dniestr declared independence in 1990 in Soviet times in response to fears that Moldova's Romanian-speaking majority would join up again with their Romanian neighbours to the south.

A brief war erupted between the two sides in 1992, halted by Russian troops who remain despite promises to leave, guarding de facto crossing points and 20,000 tonnes of Soviet-era munitions.